grounding outdoor ethernet cables

Discussion in 'Electrical Forum discussion & Blog' started by tandavad, Jan 17, 2012.

  1. tandavad

    tandavad New Member

    Messages:
    3
    Location:
    California
    I have a shielded, outdoor ethernet cable running between two rural buildings. The Cat5 cable is shielded with a metallic sheath and has a drain line running through it to both ends for grounding purposes. I bought two L-Comm weatherproof lightning surge protectors and installed one at each end of the 250' cable. There are two shorter Cat5 cables connected to the lightning protectors which go on into each building. There are also grounding wires going from each lightning surge protector to a grounding rod located at each building. The system worked fine for about six months, then became erratic, and finally stopped working. After testing to see where the signal was interrupted, I came to the conclusion that the cable was defective and replaced it with a new one which, frustratingly, did not work either. After a lot more testing, I finally isolated the problem somewhat more specifically. If I disconnect the grounding wires from both lightning protectors, the signal goes right through from a router in one building to a computer in the other building. If I reconnect either one of the grounding wires the line is dead at the far end. I got conflicting advice about whether to ground both protectors (the issue being ground loops), but the company told me to ground both of them as they were 250' apart. Technical support at L-Comm has no idea what the problem is and advised me that they may have been damaged by lightning and to buy new ones (at about $70.00 each). I'm reluctant to do this when the signal runs through the lightning protectors just fine without the ground wires being connected to them. It seems to me that there might be a simple solution that no one has thought of. Any suggestions to this grounding problem would be appreciated
  2. jwelectric

    jwelectric Electrical Contractor/Instructor

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    To clear up this problem you will need to buy two new surge protectors as the ones you have now have done their job to the point of failure. Should you decide not to then the computer will be the protector next time
  3. LLigetfa

    LLigetfa DIYer, not in the trades

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    Location:
    NW Ontario, Canada
    +1

    Are the ground rods bonded to the building ground? Ethernet over CAT5 cable between buildings with possible ground potential differences can be fraught with issues. I say, rip it out and go with fiber optic cable instead. I do a lot of outdoor CAT5 stuff for APs and cameras, but not so much between buildings. Between buildings I run fiber.
  4. DonL

    DonL Jack of all trades Master of one

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    The Drain in the wire is for Shielding, Not Grounding and should not be connected to Ground.

    But the Protectors need to be connected to ground, before they will protect properly.

    Chances are only 1 of the protectors is bad, remove them completely to determine the bad one.
  5. DonL

    DonL Jack of all trades Master of one

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    Fiber would be nice, but the transceivers can get a bit pricey.

    Wireless may be a cheaper option.
  6. jwelectric

    jwelectric Electrical Contractor/Instructor

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    The shielding is the ground Don
  7. DonL

    DonL Jack of all trades Master of one

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  8. jwelectric

    jwelectric Electrical Contractor/Instructor

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    Location:
    North Carolina
    also for your reading pleasure

    800.100 Cable and Primary Protector Bonding and Grounding.
    The primary protector and the metallic member(s) of the cable sheath shall be bonded or grounded as specified in 800.100(A) through (D).
  9. DonL

    DonL Jack of all trades Master of one

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    So how do you suggest the Shield in a cat5 cable to be connected ?

    Teach us something, Please.
    Last edited: Jan 17, 2012
  10. jwelectric

    jwelectric Electrical Contractor/Instructor

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    Location:
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    I am not an IT person so I leave that in your hands. But I know that it has to have an earth connection and without one the equipment will suffer the total of a lightning strike
  11. DonL

    DonL Jack of all trades Master of one

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    I agree that It is very important that the Protector has a earth connection to a ground rod, But Cat5 normally has no shield in the first place.

    Using Shielded Cat5 is a waste of money, unless it is running parallel with other Interfering conductors. That is what the twisted pair is for.

    Normally the shield just ends at the jack, Because there is no place to connect it. If you do connect it to Ground on Both ends you could get a TRUE Ground Loop big time.


    Been there seen that.
  12. BobL43

    BobL43 DIY Senior Member

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    Yavol, yavol!
  13. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
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    Location:
    NW Ontario, Canada
    I use variety of protectors from DataLinx, Ditek, and L-Com to name a few. Some protectors ground the shield and some don't. Some are designed specifically to allow for POE voltages. The AL-CAT5VW I use has no shield ground while the BT-CAT5-P1J does but it is not really considered entrance protection since it injects POE power..

    The shield ground can cause problems with ground loops so in some cases, we isolate the far end, not the entrance. As per code, the entrance must be grounded.

    Rather than use STP, I generally will use UTP that is sheathed in armor. My favorite is rodent resist direct burial that has a tough metallic sheath that rodents have a hard time to chew through.
  14. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
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    Location:
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    The drain wire on STP connects to the metal hood of the RJ45 plug and some RJ45 jacks do accommodate it with an electrical connection, so I really don't know what you mean by "normally".

    Here is a link for UBNT ToughCable:

    http://www.ubnt.com/toughcable
    Last edited: Jan 17, 2012
  15. DonL

    DonL Jack of all trades Master of one

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    Even with the power over Ethernet the Negative Conductor does not go to ground. (Or very rarely, No standard Yet)

    If you do connect the shield then it is best to do it at the Router. (Place of signal origin)

    There is little code that covers Low Voltage , Low current Connections.
  16. DonL

    DonL Jack of all trades Master of one

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    Also If you do try to use Power Over Ethernet and the protector quits working, You may have blown one of the Schottky diodes. $.50 Cent fix...
  17. tandavad

    tandavad New Member

    Messages:
    3
    Location:
    California
    That's what L-Com told me too. They said to consider them disposable, but $75 each sounds like a pretty expensive disposable item--especially when several severe lightning storms a year are to be expected in my area. L-Com also suggested that there were other alternatives to their product for ethernet lightning protection,, but they would be much more expensive. They also told me that there was no warranty period for lightning damage and as I had indicated that there had been a serious lightning storm during the six months I had installed, the company would not replace them.
  18. tandavad

    tandavad New Member

    Messages:
    3
    Location:
    California
    Thanks for the response. In answer to your question: The property is in an off grid location. Each building has a ground rod to which everything in each buildings is grounded including the building wiring, the inverters, and (in the case of the main building) a Hughes satellite dish. There is also another grounding rod at the solar panels which are mounted about 125 feet from the house. When I installed the solar panels, they were too far away from the house to ground them to the primary ground rod there, so I put in a separate ground rod at the base of the solar mounting structure. Perhaps that has caused some ground loop problems; but in four years, I have never had any problems until I ran the ethernet cable to the other building. And even then, I had no problems for the first six months. There was a very severe lightning storm which fried a computer that was connected to the phone line (thankfully, no damage to any equipment connected to the ethernet cables), but the problem with the surge protectors did not become evident immediately after that storm. The problem began a week or two after the storm and was intermittent for several weeks and finally there was just no signal at the far building. Right now, the cables are connected to the lightning protectors and the signal is fine; but as soon as I connect one of the protectors to ground, the signal is gone. So I assume that I really have no protection at present. (I have not tried disconnecting the ground at the solar panels; but as I mentioned, everything worked fine for the first six months.) I bought the shielded cable primarily because it was an outdoor cable--I don't really need the shielding because the system is way out in the country, and the issue of interference is pretty nonexistent. I might add that I live in a very rocky area and it would be impossible (at least, very difficult) to bury the cable, so I have it going through the air supported by a vinyl sheathed steel cable--don't know if you can run fiber optic through the air, but price was also an issue for me as the internet connection in the secondary building was not of critical importance.
  19. DonL

    DonL Jack of all trades Master of one

    Messages:
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    Location:
    Houston, TX

    Take them apart and replace the Bad Diodes.
  20. bcdudley

    bcdudley New Member

    Messages:
    15
    Location:
    Texas
    It may be a little late for this, but I had the same problem. I picked up a couple of older model used switches from **** for about $50 each. They came with transceivers. I then ran the fiber cable from rooftop to rooftop and down the wall to the switch. It has been working great for several years now. The buildings were about 100 yards apart.

    I have heard of before, but never seen where a computer had a bad ground and tried to use the cat 5 cable as a ground, causing some sort of ground loop between the buildings.
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